Hydraulic brake mechanism for tractor steering



June 12; 1951 A. N. MILSTER 2,556,287

HYDRAULIC BRAKE MECHANISM-F0R TRACTOR STEERING Filed Feb. 4, 1946 B 'l A ORNEY Patented June v12A, 1951 HYDRAULIC BRAKE MECHANISM FOR TRACTOR STEERING Arthur N. Milster, Ferguson, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo.,

a corporation of Delaware Application February 4, 1946, Serial No. `645,256

(Cl. 18S- 152) 10 Claims. l

This invention relates to tractor steering controls andv one of the objects thereof is to provide a dual opposed piston cylinder constructionin which the pistons may be selectively operable'to selectively actuate either of the brake mechanisms on the tractor drive wheels to assist steering or they may be jointly operable to` arrest traverse of the tractor.

Another object of the invention is to provide a dual opposed piston cylinder construction for producing pressure fluid to actuate the braking mechanism associated with the drive wheels of the tractor in which the piston cylinder devices may jointly operate said brakes to arrest vehicle motion and in which manual means are provided to enable the operator to cause the piston cylinder devices to become severally operable to assist the steering of the tractor.

In the drawings Figure 1 shows a sectional elevational view of the brake control; and

Figure 2 shows a sectional view along the line 2-2 of Figure 1.

A casing I suitably secured to the tractor frame 2 (only a portion of which is illustrated) has a member 3 suitably arranged therein which has a tubular formation 4 formed thereon in I which a dual opposed master cylinder 5 is slidably received. The casing also serves as a reservoir for a suitable brake operating fluid. Suitable seals 6 and 1 are arranged in the tubular housing 4 to prevent leakage of brake operating uid from casing I and a seal 8 may be arranged at the upper end for similar purposes. Arranged in each end of master cylinder 5 are pistons 9 and I provided with packing cups II and I2 and centrally disposed in master cylinder is a member I3 which is xed in the cylinder by brazing or welding to prevent relative axial motion of the member and cylinder and to prevent the passage of uid from one end of the cylinder to the other. Compensating ports I4, I4' are formed in the cylinder walls in the positions indicated and valves I5 and I6, which may be similar in construction tothose shown in United States Patent No. 2,214,045, issued September 10, 1940, are assembled in member I3, and springs I1 and I8 are disposed between piston packing cups II and I2 and the centrally disposed member I3. Valves I5 and I6 maintain uid in the associated conduits and brake mechanisms under a light pressure. Member I3 has passageways formed therein, to which conduits I9 and 20 are connected, controlled by valves I5 and I6. The conduits lead to brake mechanisms 2| and 22 which have brake shoes 23 and 24 suitably piv- 2 oted on the backing plates of each brake mechanism and brake actuating motors 25v and 26 expan'd the brake shoes into engagement with a brake drum customarily associated with the brake mechanism. Suitable resilient members 21 and 28 are provided in each mechanism to restore the brake shoes to disengaged position.

The actuating means for each of the pistons 9 andIIl are pedals 23 and 30. Pedal 30 is secured to a shaftk 3| rotatably mounted in suitable journals in casing` I. Pedal 29 issecured-to a sleeve 32 telescoped on a reduced diameter portion of shaft 3I. which is secured to shaft 3| and is engageable with piston Ill in master cylinder 5. Sleeve 32 has a sprocket sector 35 rigidly secured thereto and a chain 35 has one end thereof connected to sprocket sector 35. A second shaft 31 is rotatably mounted in casing I in suitable journals and has an arm 38 connected thereto which is engageable with piston 9 in master cylinder 5. A sprocket sector 39 is rigidly secured to shaft 31 and chain 40 has one of its ends secured to the sprocket sector 39. A turnbuckle 4I connects the free ends of chains 36 and 40 and provides a means for adjusting the relative free positions of lever arms 33 and 38. The sprocket sectors may be eliminated and chains 36, 4I) connected securely to wheels or-similar constructions.

The centrally disposed member I 3 has a cavity Y42 formed therein and one end of a rod 43 axially movable in the supporting member 3 is insertable in cavity 42. Rod 43 extends above casing I and is provided with a reduced diameter end 43a which has a cap 44 secured thereto. A boss 45 is formed on casing I in the position shown in which shaft 43 moves. A spring 46 engages cap 44 and a shoulder 41 on boss 45 engages the other end of the spring, spring 46 normally urging the shaft to the position shown. A lateral extension 45a of the housing has a bore therein in which a member 48 is slidably received. A plug 49 is received in the bored end of member 48 and a spring 50 urges the plug to the position indicated in the drawings. The plug 49 is engageable with shoulder 5I on rod 43 and when said plug engages said shoulder, the opposite end of rod 43 will extend into cavity 42 formed in member I3. A speed control device 52 which is prefera bly a gear shift lever adjustable to a plurality of positions such as low, intermediate, high and reverse, customarily associated with tractor vehicles has a rod 53 connected thereto which also engages the movable member`V 48, there being a suitable socketed connection between rod 53 and Arm 33 is formed on a member 34 v said movable member. When the speed control device 52 is in certain positions of adjustment, preferably a low gear ratio position, the movable member 48 will be moved toward rod 43, and plug 49 under these conditions will move relatively axially of the movable member 48. When it is desired to lock the master cylinder 5 in position, rod 43 is depressed by the operator to cause its entry into socket 42 and when in proper position, plug 49 will engage shoulder 5l on shaft 43 to hold it in this position as long as thespced control device remains in the predetermined position.

The operation of this device ito assist .steering of the vehicle, which is customary during vlow traverse speed operation of the tractor, will require the operator to place the speed control-device in the low speed position, shown by the dotted line position of device 52. When this-is accomplished and the operator desires the assistance of the braking mechanisms to steer .the tractor, he will depress rod t3 to Vcause the master cylinder 5 to be held rigidly in the cylinder holding member ii. W hen this has been accomplished the selective actuation of pedals 29, Aand SSW/ill selectively apply the brake mechanisms 2l and 22, the lat-ter being associated with the righthand and left-hand drive Wheels, respectively, of the tractor. Depending upon the .direction it is desired to turn the tractor, brakes 2l and 22 will be applied so that the drivewheel associated with the respective braking mechanism will be held stationary or be allowed to zrotate, it being assumed that brakezmechanisi- ElV for the righthand wheel will beheld `stationary when it is desired to turn tothe rightgandivvhen it is desired to turnto the left, the Ybraise mechanism 22 will be applied.

During 'the high speed :operations of the vehicle, it will not be possible to ,selectively actuate the brakes because the speed control device will have withdrawn the Ymovable member dit and plug it associated vtherewith from engagement with rod 43 enabling spring l5 to lift it to the position illustrated in Figure l. In vthiscondition of operation, actuation 4ci -either brakepedal 29 or 3l? will apply both brakes `to stop the'vehicla This will be caused'by reason olithe factthat when pedal 3E), for-example, is depressedxits associated arm 33 will force piston l@ into master cylinder 5 closing compensating port lll and because master cylinder 5 may nov,T move relatively to the holdingmember il, Vcompensating port 'ifi will also be closed since arm' is heldistationary against the end of casing l and as master cylinder 5 moves relatively to the tubular holding'member li it will of necessity move relatively to piston 9. rThe force applied to piston i@ Will, therefore, cause pressure fluid to be developed in both ends of the master cylinder and at equal pressures to be forced past the valve mechanisms l5 and i6 into both brake cylinders '25 and 26.

Suitable slots'are formed in the ends of -master cylinder 5 to permit arms 3S and 38 to move pistons 9 and il). A suitable slot is formed in the lower portion of housing l to permit-conduits I and 2Q securedto Amaster cylinder 5 to move relatively to lcasing l. 'Since both compensating ports ld and i4 have been `covered ybecause of the relative motion of master cylinder 5 with respect to both pistons 9 and lil, it is believed clear that there is no loss oi pressure 'fluid from the master cylinder when the pistons are actuated by either of the pedals 29 .or '30. It is further obvious that if brake pedal29 should be depressed,

the action described above will occur because arm 33 will be prevented from moving by engaging with the end of casing l resulting in relative motion between piston l and master cylinder 5, piston 9 being moved by arm 38, thereby causing both brakes to be actuated simultaneously and at the same -pressure inthe manner previously set forth.

Having fully described my invention, that which I claim as novel and desire to protect by Letters Patentof the United States is:

l. A brake control comprising a casing; a cylinder; means to support said cylinder in said casing for movement along its longitudinal axis;

r a piston in each end of said cylinder; meansmin Asaid cylinder to divide it into two chambers;

brake actuating means connected to each chamber; a brake mechanism operable by each actuating means; an actuator for each piston; a brake pedal for each actuator; and means to lock said cylinder against axial movemenusaid .pistons being selectively loperable bysaid @pedals respectively when said cylinder is `locked in position, and said pistons being jointly operable by either brake pedal when said cylinder is axially movable.

2. A brake control comprising a casing; a cylinder; means .to support A.said cylinder Yin said casing for movement along its. longitudinal axis; a piston in each end .of said cylinder; a nxed wall in said cylinderdividingit into two noncoinmunicating chambers;.a brake motor connected to each chamber; abrake mechanism Voperable by each motor; an actuator for each piston; a bra'xe pedal 'for each actuator; means vto support said lbralgefzpedals :insaid :casing on .a common axis 'of rotation;.a speed control device adjustable to a plurality ofv positions;V and manually operable means..;operatively connected-ato said device to "lock saidcylinder against axial movement Aduring a .predetermined position oladjustment of said device tofenablexsaid pistons to be selectively operable, said pistonsbeing .jointly operable by either brake 'pedal-when said device is in other positions'of adjustment/to :permit movement of said cylinder 'along its longitudinal axis.

3. A brake control comprising a casing; a cylinder; means to V'support fsaid cylinder'in said casing for movement along'its longitudinal axis; a piston in each vend 'of said cylinder; a Wall in said cylinder to divideI 'it Vinto rtwo non-communicating chambers; brake actuating means operatively connected 'to 'each chamber; af brake mechanism to beV operatedby Ieach actuating means; means to locksaid cylinder against said axial movement; andmeans to individually actuate each piston to thereby individually-actuate each brake actuating ymeans when Ysaid -cylinder is locked in position Vand-to jointly actuate said pistons to thereby jointly actuate yeach' Abrake actuating means when said cylinder is capable of movement along `its longitudinal axis.

4. A brake control comprising a'casing; a cylinder; means to support said cylinder in said casing for movement along its longitudinal axis; a piston in each end of said cylinder; means in said cylinder to divide itinto two chambers; a brake motor connected to each chamber; a brake mechanism operable by each motor; an operating arm for each piston; a brake pedal for each operating arm; means to support said brake pedals for rotation about a common axis; and'means tozlock said cylinder in position, said 'pistons being findividually operable V`by .the lpedalsy Yrespectively when said cylinder is lockedin position; 'and said pistons being jointly operable by either brake pedal when said cylinder is capable of movement along its longitudinal axis.

5. A brake control comprising a housing; a cylinder; means in said housing to slidably support said cylinder for movement along its longitudinal axis; pistons arranged in both ends of said cylinder; piston operating arms supported in said housing; manually-operated members for each of said piston operating arms; a speed controlling device adjustable to a plurality of positions; means selectively engageable with said cylinder to prevent longitudinal movement thereof; and means connecting said speed controlling device and said last mentioned means to prevent longitudinal movement of said cylinder in one position of adjustment of said speed control device to thereby enable said pistons to be selectively operable, and when said speed controlling device is in other positions of adjustment said cylinder is axially movable in said casing so that both of said pistons may be simultaneously operated by either of said manually-operated members.

6. A brake control comprising a brake assembly for each traction element of a vehicle; a casing; a two chamber cylinder, each chamber operatively associated with one brake assembly; means mounting said cylinder in said casing for longitudinal movement along its major axis; a piston slidably mounted in each chamber in said cy1inder; individual actuating means for each piston; and selectively operable means constructed and arranged for engaging said cy1inder for preventing longitudinal movement thereof for permitting said pistons to be selectively or simultaneously operated by said piston actuating means, simultaneous actuation being produced by either of said piston actuating means when said cylinder is free to slide in said casing.

7. A brake control comprising a casing; a cylinder; means in said casing mounting said cylinder for longitudinal movement along its major axis; a piston in each end of said cylinder; means in said cylinder dividing it into two chambers; a brake actuating motor connected to each chamber; a brake mechanism to be operated by each brake actuating motor; individual actuating means for each piston; means for engaging said cylinder for preventing movement relative to said casing, said brake control being constructed and arranged for permitting joint or selective operation of either of said brake motors, the joint operation of said motors being produced by either of said piston actuating means when said cylinder is free to move in said casing.

8. A brake control comprising a pair of brake assemblies, each `of which is associated with the traction elements of a vehicle; a casing; a cylinder; means in said casing mounting said cylinder for longitudinal sliding movement along its major axis; means in said cylinder for forming a chamber in each end thereof, each chamber being connected to one of said brake assemblies; a

selectively operable,

piston in each of said chambers; individual actuating means for each piston; selectively operable means for engaging said cylinder for preventing relative motion with said casing, said brake control being constructed and arranged for selectively or simultaneously actuating said brake assemblies, simultaneous actuation of said brake assemblies being produced by either of said individual piston actuating means when said cylinder is movable relative to said casing.

9. A brake control comprising a cylinder; a casing; means mounting said cylinder in said casing for longitudinalsliding movement along its major axis; a piston in each end of said cylinder; means in said cylinder dividing it into two chambers; a brake operating motor connected to each chamber; a brake mechanism to be operated by each brake operating motor; individual actuating means for each piston; selectively operable means for engaging said cylinder for preventing longitudinal movement relative to said casing, said actuating means being constructed and arranged for selectively or simultaneously actuating said brake mechanism, simultaneous actuation being produced by either of said individual piston actuating means when said selectively operable means is disengaged from said cylinder.

10. A brake control comprising a brake assembly for each traction element of a vehicle; a casing; a cylinder having two chambers therein, each chamber operatively associated with one brake assembly; means in Said casing mounting said cylinder for longitudinal sliding movement along its major axis; a piston slidably mounted in each chamber; selectively operable means for engaging said cy1inder for preventing longitudinal sliding movement thereof; and individual actuating means for each piston and being selectively operable, said individual actuating means each enabling its associated piston to be selectively operated for individually operating each brake assembly when said selectively operable means engages said cylinder, either of said individual actuating means enabling both pistons to be jointly actuated, thereby jointly actuating each brake assembly when said selectively operable means is disengaged from said cylinder.

ARTHUR. N. MILSTER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,584,358 Dement May 11, 1926 1,824,062 Winter Sept. 22, 1931 2,115,558 Noack Apr. 26, 1938 2,362,521 Acton Nov. 14, 1944 2,367,194 Boldt Jan. 16, 1945 2,374,196 Harbers Apr. 24, 1945 FOREIGN PATENTS Number Country Date 346,139 Great Britain Apr. 9, 1931 

